Emulsion copolymerization of isobutylvinyl ether and vinyl chloride

ABSTRACT

A PROCESS FOR PREPARING COPOLYMERS OF ISOBUTYLVINYL ETHER AND VINYL CHLORIDE HAVING AN NREL (1% WEIGHT/ VOLUME IN TOLUENE) OF 1.3 TO 1.5, A VOLUME STRENGTH OF 3,000 TO 5,000 P.S.I.G., AND AN ELONGATION OF 3.5 TO 7%, WHICH CONSISTS OF COPOLYMERIZING ISOBUTYLVINYL ETHER AND A PORTION OF THE VINYL CHLORIDE TO BE POLYMERIZED IN AN AQUEOUS PHASE CONTAINING A HIGH PURITY SODIUM ALKYL SULFATE AND POTASSIUM PERSULFATE SO AS TO YIELD A 40-50% CONVERSION FOLLOWED BY EQUAL INCREMENTAL ADDITIONS OF THE REMAINING PORTIONS OF THE VINYL CHLORIDE TO BE COPOLYMERIZED FOR A PERIOD OF TIME UNTIL CONSTANT PRESSURE IS OBTAINED, AND SUBSEQUENTLY ISOLATING THE RESULTANT COPOLYMER BY COAGULATION WITH A PRIMARY ALIPHATIC ALCOHOL OR A WATER-SOLUBLE SALT OF A POTASSIUM CATION.

United States Patent Oflice p 3,741,946 Patented June 26, 1973 3,741,946EMULSION COPOLYMERIZATION F ISOBUTYL- VINYL ETHER AND VINYL CHLORIDEWiley E. Daniels, Easton, Pa., assignor to GAF Corporation, New York,N.Y.

No Drawing. Continuation of application Ser. No. 594,651. Nov. 16, 1966.This application Aug. 7, 1970, Ser. No. 62,134

Int. Cl. C0815 1/60 U.S. Cl. 260-875 G 7 Claims ABSTRACT OF THEDISCLOSURE A process for preparing copolymers of isobutylvinyl ether andvinyl chloride having an 1 1% weight/ volume in toluene) of 1.3 to 1.5,a volume strength of 3,000 to 5,000 p.s.i.g., and an elongation of 3.5to 7%, which consists of copolymerizing isobutylvinyl ether and aportion of the vinyl chloride to be polymerized in an aqueous phasecontaining a high purity sodium alkyl sulfate and potassium persulfateso as to yield a 40-50% conversion followed by equal incrementaladditions of the remaining portions of the vinyl chloride to becopolymerized for a period of time until constant pressure is obtained,and subsequently isolating the resultant copolymer by coagulation with aprimary aliphatic alcohol or a water-soluble salt of a potassium cation.

This application is a continuation of Ser. No. 594,651 filed Nov. 16,1966 and now abandoned.

This invention relates to an improved process of copolymerizingiso-butylvinyl ether and vinyl chloride by the emulsion technique to ahigh molecular weight copolymer which has improved film strengthcharacteristics and other improved properties.

The emulsion copolymerization of iso-butylvinyl ether and vinyl chlorideis well known in the polymer art. The details of the manufacture of suchcopolymers have been reported by C. E. Schildknecht in his book Vinyland Related Polymers, pp. 408, 409, published by John Wiley & Sons,Inc., New York (1952); and in P. B. Report 485, p. 62; J. G. Kern(1945). These publications report that the emulsion copolymerization ofiso-butylvinyl ether and vinyl chloride (30/70 weight ratio) wasconducted at a temperature of 30-50 C. The aqueous phase contained 6% ofsurfactant (Mersolat, a sodium alkyl sulfonate) 0.1 to 0.3% of potassiumpersulfate and a phosphate buffer to maintain the pH near 7.0. Theaqueous/monomer ratio was 75/25. The vinyl chloride was addedportionwise to the reacting iso-butylvinyl ether monomer. Conversionswere apparently less than 100%, since unreacted monomer was presentwhich was not recovered. A later reference, M. F. Shostakovskii et al.,Jhurnal, prik. Khim. 28, (1955) 1123-1127, disclosed a maximumconversion of monomers to polymer of 80.5% after 48 hours at 30 C. in anautoclave. Again, a sodium alkyl sulfonate was used as surfactant.

The copolymer prepared as described in the foregoing references has beensuggested for use in the surface coating industry because of itssolubility in a variety of organic solvents. The molecular weight of thecopolymer is such that a 1.0 weight/volume percent solution in toluenehas an 1 of 1.289. A 10 mil film prepared from the copolymer by Carverpressing has a tensile strength of 1200 p.s.i.g. and an elongation ofonly 1.8 percent and is very brittle. Such copolymer would find greaterfavor in the surface coating industry if the films thereof had improvedfilm strength properties, which impart durability to dried lacquer andpaint films.

It is the principal object of the present invention to provide animproved process for emulsion copolymerization of isobutylvinyl etherand vinyl chloride to a higher molecular weight and of higher filmelongation and of higher film strength.

Other objects and advantages will become manifest from the followingdescription.

In attaining the foregoing objects, the emulsion copolymerization iscarried out at temperatures of 30-40 C.,the vinyl chloride being addedto the iso-butylvinyl ether/vinyl chloride mixture in a programmedmanner, as will be evident from the following general process detailsand illustrative working examples. A very high level of surfactantpurity is an absolute necessity in carrying out the copolymerizationreaction, such as sodium alkyl sulfate, wherein the alkyl is from 8 to16 carbon atoms and of 95 to 99.5 percent assay. The product of thecopolymerization is then isolated from the latex by means of coagulationWhile employing potassium salts such as potassium chloride, potassiumacetate and potassium sulfate, etc., so as to provide a copolymer ofhigh purity containing very small amounts of non-polymeric solids asdetermined by the ash content. Instead of potassium salts, a primaryaliphatic alcohol of from 1 to 4 carbon atoms may be employed as thecoagulating medium in the ratio of 1 part by volume of latex to 2 partsby volume of said alcohol to yield a copolymer of high purity.

In general, the improved process comprises copolymerizing iso-butylvinylether and vinyl chloride (30/70 total ratio) to higher molecular weightcopolymers having higher film elongation and higher film strength by thereaction of the following components in a sealed pressure vessel such asan autoclave at 30-40 C.

The parts given are by weight unless otherwise noted. 30 parts ofiso-butylvinyl ether and 30 parts of vinyl chloride are added togetherat 3040 C. into an aqueous phase consisting of 300 parts of water, 12parts of sodium alkyl sulfate, such as sodium octyl sulfate, sodiumnonyl sulfate, sodium decyl sulfate, sodium lauryl sulfate, sodiumtridecyl sulfate, sodium pentadecyl sulfate, and sodium cetyl sulfate of95-99.5% assay, 3.8 parts of anhydrous monobasic sodium phosphate (NaHP0 2.4 parts of 50% aqueous sodium hydroxide solution to give a pH of7.5-12, and 0.9 part of potassium persulfate for a period of time of 4-5hours or until 40-50% conversion has occurred (as determined by solidscontent), followed by the addition of 40 parts of vinyl chloride in 4equal increments, and allowing each increment to react at 30-40 C. for aperiod of up to two hours, followed by continuing the reaction until alow constant pressure value of about 0 to 4 p.s.i.g. is obtained.

The resultant latex is coagulated most efliciently by adding the latexto a lower alcohol of 1 to 4 carbon atoms or to a solution of apotassium salt in water so that the volume of water will be ca. fivetimes the volume of latex and that theweight of potassium salt containedtherein will be about one-fifth the weight of latex. The coagulatedpolymer is then washed with stirring in an amount of water equal to 10times the original latex volume while heating to 65 to 70 C., andfiltering quickly at that temperature. The isolated copolymer is thenvacuum dried to constant weight to yield 90-95% recovery of copolymerfrom the original latex. The resulting copolymer contains low quantitiesof non-polymeric solids, e.g. ca. 0.01- 0.04% dry ash, and is composedof from 70 to vinyl chloride, but most commonly about 71-73% vinylchloride, and has an 1 in toluene (1.0 w./v. percent) of 1.3 to 1.5,mostly a value of about 1.4.

It is also possible to carry this copolymerization out at 29% solids orat 40 or at 51% solids concentration as will be shown in the detailedillustrative examples. When working at 50% solids, the pH must be raisedto a value of about 12 and slightly more potassium persulfate must PhaseA (prepared in 22 liter flask) be used, as will be noted from Examples Vand VI.

The following table shows the comparison between the 72 grams of KH POwas dissolved in 6000 grams of new and improved features of thecopolymerization procdistilled water (pH 4.5-4.7). Then 25 cc. of 50%NaOH ess and the resulting copolymer of the present invention 5 wasadded (pH 7.5-8.0). To this was added 240 grams and the process of theprior art described by C. E. Schildof sodium lauryl sulfate 99.5% assay.This mixture was knecht, referred to above: then stirred for severalhours. To the mixture was added Detail Prior art Instant processTemperature. 30 to 50 C 30 to 40 C.

Surfactant type Alkylarylsulfonate Sodium alkylsuliate 95 to 99.5%.

Surfactant coneentratiom. 6% in aq. phase... 3.5% to 4.5% in aq. phase.

1) ear 7 7 to 12.

Reaction time Undlscloscd.- 24 to 30 hours.

Manner of monomer ddi IncrementaL. Incremental Conversion Less than100%- 98 to 100%.

Ratio monomer to aqueous phase... 1:3 From 1:3 to 1:1;

Copolymer isolated by p ym r met (1% toluene) copolymer film strengthAIZ(SOJ)3 coagulation. Lower alcohol or potassium salt coagulation.1.289

1.3 to 1.5. I

83535313? .II i) 101 to 0.0%:

The following examples will specifically illustrate how 18 grams ofpotassium persulfate and agitated for minthe foregoing objects areattained. The parts given are by utes. welght unless otherwlse nowd'Phase B (prepared in a steel pressure cylinder.)

EXAMPLE I 25 600 grams of vinyl chloride was evaporated from the Thefollowing aqueous phase was prepared: rnain cylinder through a KOHpacked tube (to remove phenol stabilizer) and condensed into a cylindercontaing i2 ing 600 grams of isobutyl vinyl ether (assay by VPC i of 50%i f solution (PH 7 5) 99.9% Phase A was charged into the S-gallonautoclave.

The autoclave was then purged of air by pulling a vacuum to about 50 mm.Hg and releasing with nitrogen. This was repeated three more times. Thecontents were then This was placed in a 1.0 liter magnetically stirredautoh d to 30 C Phase B was then chargcd and the clave which was sealedand pressure tested. The autoclave io ll d t e d f 4% hours D i thiperiod s evacuated to 1 of then filled With 2 t0 1 the pressure droppedfrom 30 to 27 p.s.i.g. and the temper- P- J- This was repeated threetimes. and the ature held constant at 30 C. After the 4% hours a sample12.0 grams of sodium lauryl sulfate 99.5% assay, and 0.9 gram ofpotassium persulfate.

temperature raised 10 C" and maintained there 6166- was taken andindicated 8.4% solids or 40.3% conversion. tronically. At this time 200grams of vinyl chloride was added and There was then added to theautoclave from a stainless h reaction continued at 30 C, f 2 more h Asteel t a cylinder. a mixture consisting of 300 a 40 sample after thetwo hours indicated 14.0% solids or of i y y ether and grams of vinylChloride 63.1% conversion. Pressure dropped from 44 to 24 p.s.i.g. andallowed to react for 4% hours at 30 C., during which A hi i 200 grams ofvinyl hl id was dded a d time the internal pressure remained at 36p.s.i.g. At the h ti continued t 30 C, f 2 more ho r A end of this timegrams of Vinyl Chloride Were added sample after the two hours indicated22.2% solids or and a lowed t r ct for tWO hours at P 90.6% conversion.Pressure dropped from 44 to 4 p.s.i.g. fell from 46 to 24 p.s.i.g.Another 10.0 grams of Vinyl At this time 200 grams of vinyl chloride wasadded and Chloridfi Were added, reacted for tWO hours t 30 C-, thereaction continued at 30 C. for 2 more hours. A pressure fell from 41 to10 p.s.i.g.Athird 10.0 gram incresample after the two hours indicated23.8% solids or ment of vinyl chloride was added and reacted 2 hours at90.1% conversion. Pressure dropped from 40 to 0 p.s.i.g.

C" PresSure fell from 40 to 10 P- -g- The fourth At this time 200 gramsof vinyl chloride was added and increment of 10.0 grams of vinylchloride was added and 50 the reaction continued at 30 C. for 2 morehours. A allowed to react to a constant pressure value of 4 p.s.i.g. atsample after the two hour indicated 26.8% solids or a total reactiontime of 18 hours. The product was a thin 95.0% conversion. The reactionwas continued at 30 C. fluid copolymer latex of 28.0% solids (29.0%theoretical) for an additional 1 hour until the pressure had dropped to(96.5% conversion) and pH 7.0. 0 p.s.i.g. The final sample indicated27.6% solids or 98.0% A sample of polymer was obtained by coagulationwith conversiomThe polymer slurry was then discharged from methanol, andrepeatedly washed with water, and dried to the autoclave and was a fluidwhite latex.

constant weight. The copolymer on elemental analysis con- The copolymerisolation was carried out in a 30-gallon tained 48.9% C, 6.7% H, 41.8%Cl, 0.34% ash (calcustainless steel drum 18", dia. x 31" high andequipped lated for a 30/70 iso-butyl vinyl ether/vinyl chloride cowith aturbine, 8" dia., with 6 blades and spinning at 100 polymer was 39.8%C1) or ca. 73.2% PVC, 27.8% isor.p.m. A steam coil in the drum isprovided for heating.

butyl vinyl ether. The 1 of a 1.0 w./v. percent toluene Into the drumwas charged 10 gallons of distilled Water solution was 1.36. Thecopolymer had a Parr melting range and to this was added 1480 gramspotassium chloride of 92-l07 C. and Was Carver pressed into a 10 milfilm and the mixture agitated until the salt dissolved. 7400 having atensile strength of 3300 p.s.i.g. and an elongation cc. of copolymerlatex (from above copolymerization) of 4.2% as determined by an lnstrontensile test. was then added to the KCl solution to coagulate thecopolymer. The batch was agitated 15 minutes; then EXAMPLE H -thecoagulated copolymer from the drum was removed This example illustratesa twenty-fold scale-up of the a a olid by filtration, The copolymer cakewas then polymerization process of Example I, and the isolation ofreturned to the drum and slurried with 20 gallons of the copolymer bymeans of KCl coagulation. distilled water. This mixture was then heatedto 70 C.

The -s autoclave was thoroughly cleaned and co and while heating, 12 cc.of 50% NaOH was added to ditioned prior to polymerization by boiling upto 70 grams raise the pH'to about 7.5-8.0. At 70 C. the batch was ofpotassium pcrsulfate per 3 gallons distilled water for 1 again filteredand the final cake washed with methanol. If hour, followed by a rinsewith distilled water. facilities are available for removing water, themethanol The following mixtures were then prepared: wash is notnecessary.

The cake resulting from the filtration was then ground in a. Wiley millwith a coarse screen to help the drying. Drying was done in a vacuumoven at 40 C. for about 24-48 hours to attain constant weight. Percentrecovery of polymer was 94.2 in this run.

6. (1.0 w./v. percent in toluene), a melting range of 96- 105 C., and atensile strength of 2330 p.s.i.g., with an elongation of 4.0%. Thuswhile a good tensile strength was obtained, the copolymer did notcontain the desired 5 amount o isobutyl vinyl ether. This copolymercontained 75% PVC by elemental 6 EXAMPLE V analysls, and a 1.0 w./v.percent toluene solution had an D a of 1.37. A sample melted at 90-l00C., and a 10 Tins example illustrates the copolymenzatlon of isomilCarver pressed film had a tensile strength of 3,200 ty Vinyl ether andvinyl Chloride at C- and at p.s.i.g. and 4.5% elongation. 10 solids. Q I

EXAMPLE In An aqueous phase consisting of 300 grams of distilled water,12 grams of sodium lauryl sulfate of 99.5% assay, This example is atabulation (Table I) of several (20- 4 grams of Na HPO and 1.5 ml. of50% sodium hypolymerizations which were carried out by the generaldroxide solution was prepared and had a pH of 12.0. To procedure ofExample I at about 29% solids. This tabula- 15 this was added 0.2 gramof potassium persulfate and tion shows (1) the reproducibility of thecopolymerizathe whole heated to 65-70" C. while stirring and held attion, (2) the improved yield of isolated copolymer when this temperaturefor 1 /2 hours with a few N bubbles using KCl as coagulant vs. aluminumsulfate, and (3) that trickling through. At the end of this time thesolution was the degree of conversion of increment 1 (Phase B) is thecooled to room temperature, and 0.9 gram of potassium controlling factorin the ultimate tensile strength of the persulfate added. The aq phasewas then reacted copolymer. with a mixture of 60 grams of isobutyl vinylether and It will be noted that the polyvinyl chloride content of 60grams of vinyl chloride for 4% hours at 30 C. as in the copolymerapproaches the ideal 70% only at initial Example I. The final portion ofvinyl chloride, 80 grams, conversions on increment (1) of 65%. It willalso be was then added to the reaction mixture in 4 equal innoted thatthe tensile strength of the copolymer is 3000 crements over aneight-hour period allowing 2 hours for p.s.i.g. only when increment (l)is ca. 40 5()% coneach increment to react before addition of thesucceeding verted to copolymer. increment. After all the vinyl chloridehad been added,

It will be further noted that the overall reaction is highly h rea i n ws ntinue for fifteen hours when a presreproducible as shown by the finalconversion, and copolysure of 1 p.s.i.g. was reached. The product was abluemer m columns specifically. white latex of low viscosity, pH 11.1,and containing The tabulation also shows the improved yields of co-41.2% solids (42.1% theoretica polymer from coagulation by using KCl ascoagulant The latex Was Coagulated methanol and the P y rather thanaluminum sulfate as has been taught in the therefrom purified by Washingwith water. After drying prior art. The reason for this is that Al (s0reacts with to st w g h pr was an lyze an foun sodium alkyl sulfate toproduce aluminum alkyl sulfate to be composed of 47.6% C; 6.90% H;41.42% Cl corwhich precipitates with the copolymer and can only beresponding to isobutyl Vinyl ether and 73% P removed by washing with hotNaOH solution at which vinyl chloride- The P Y had all 'flrel Value ofpoint a great part of the polymer is re-emulsified. With as measured 011a Manhe iIn block, and Could be KCl, potassium alkyl sulfate is formed,which can be re- Carver pressed into 10 mil films which showed a tensilemoved from the copolymer by washing with Warm (50- 4 strength of 5,700p.s.i.g. and an elongation of 6.2%. 80 C.) water without copolymerre-emulsification, the EXAMPLE VI potassium alkyl sulfate beingapparently not a very good emulsifying agent. An aqueous phase of thesame composition was pre- TABLE I Copoly- Copoly- Percent conversion forPercent Latex, Final mer, mer, Copolymer Copolymer, Copolyincrementcopolymer Exp Latex percent converpercent percent 7 1-51. (1.0 percentmer, Coaguyield from No. pH solids sion 01 P'vC toluene) elongationtensile 1 2 3 4 5 lant coagulation 38.6 69.0 1. 39 41.3 72.5 1.34 4.393.6 A17(SO4)3 41.0 72.0 1.35 3.4 46.5 40.5 71.0 1.32 3.4 35.0 42.174.0 1. 37 4.3 28.6 41.9 73.6 1.36 3.5 47.8 43.3 76.5 1. 39 4.6 87.842.85 75.2 1. 37 4.5 94.2 43. 2o 76. 4 1. 35 3. 9 95. 5

EXAMPLE IV (COMPARATIVE) This example shows the adverse effect on thecopolymerization and the copolymer properties when a surfactant ofpurity less than 95% assay is employed.

In this example the procedure of Example III was followed with theexception that 99.5% assay sodium lauryl sulfate was replaced by thesame amount of sodium lauryl snrfate of 93% purity.

The reaction of increment 1 was very poor, no pressure drops beingnoted. Also, no pressure drops were noted during the time allowed forincrements 2, 3, 4 and 5. Only after all monomers were charged and atotal of nine hours had elapsed did pressure drops commence. The tfinalpressure was only 7 p.s.i.g. The final latex contained 26.4% solids(90.5% conversion). The isolated copolymer contained 77% polyvinylchloride by elemental analysis instead of the desired -72%, had an ar of1.4

pared in the same manner as in Example V with the exception that 2.0grams of potassium persulfate Were added instead of 1.1 gram. The pH ofthe solution was 12.0.

The aqueous phase was reacted at 30 C. in the same manner as in ExampleV with a mixture of grams of isobutyl vinyl ether and 90 grams of vinylchloride for 4% hours. There was then added in increments as in ExampleI a total of grams of vinyl chloride and reaction allowed to proceed to0 p.s.i.g. which required 13 hours. The product was a blue-white latexof low viscosity which had a pH of 8.7, and contained 51.2% solids(51.4% theoretical).

A sample of copolymer isolated and purified as in Example I had thefollowing characteristics:

Percent C, H, Cl: 47.45; 6.67; 43.06 indicating 75 polyvinyl chloride bycarbon content.

n 1.438 as measured in a 1.0 w./v. percent solution in toluene EXAMPLEVII The copolymerization of Example I was repeated in its entirety withthe exception that the autoclave was run at 40.0 C.

The results were very similar with the exception that slightly morepre-coagulation occurred during synthesis so that a latex (pH 10.1) ofonly 49.5% solids (51.4 theoretical) was obtained.

I claim:

1. The process of preparing copolymers of isobutyl vinyl ether and vinylchloride which comprises copolymerizing to about 91 to 99% conversion ina pressure vessel, about 24 to 31 parts by weight of isobutyl vinylether and incrementally adding thereto about 76 to 69 parts by weight ofvinyl chloride in an aqueous phase containing potassium persulfate ascatalyst and about 3.5 to 4.5% based on the weight of the aqueous phaseof sodium alkyl sulfate of at least about 95% assay as surfactant, inwhich the alkyl group contains from 8 to 16 carbon atoms, at atemperature of about 3040 C. for a period of time until a constantpressure value of about to 4 p.s.i.g. is obtained in said pressurevessel, and then isolating the said copolymer from the reaction medium.

2. The process according to claim 1 wherein the sodium alkyl sulfate issodium lauryl sulfate.

3. The process according to claim 1 wherein the said copolymer isisolated from the reaction medium by coagulation with a primaryaliphatic alcohol of from 1 to 4 carbon atoms.

4. The process according to claim 1 wherein the said copolymer isisolated from the reaction medium by coagulation with a water solublesalt of a potassium cation.

5. The process according to claim 1 wherein the sodium alkyl sulfate issodium lauryl sulfate of 99.5% assay.

6. A process as defined in claim 1 wherein there is employed about 30parts by weight of isobutyl vinyl ether and about 70 parts by weight ofvinyl chloride.

7. A process as defined in claim 6 wherein said 30 parts of isobutylvinyl ether are first polymerized with about 30 parts of the vinylchloride for a period of time to yield a conversion of -50%, followed byaddition of about 40 parts of the vinyl chloride to the reaction mediumin 4 equal increments.

References Cited UNITED STATES PATENTS 2,016,490 10/1935 Fikentscher26087.5 G

OTHER REFERENCES Williams L.: Polymerization in Emulsion in PolymerProcesses Ed., Schildknecht, pp. 137 and 138, 1956.

JOSEPH L. SCHOFER, Primary Examiner S. H. LEVIN, Assistant Examiner

